Lamington is an andesitic stratovolcano with a 1.3-km-wide breached summit crater containing a lava dome. Prior to its renowned devastating eruption in 1951, the forested peak had not been recognized as a volcano. Mount Lamington rises above the coastal plain north of the Owen Stanley Range. A summit complex of lava domes and crater remnants tops a low-angle base of volcaniclastic deposits dissected by radial valleys. A prominent broad "avalanche valley" extends northward from the breached crater. Ash layers from two early Holocene eruptions have been identified. After a long quiescent period, the volcano suddenly became active in 1951, producing a powerful explosive eruption during which devastating pyroclastic flows and surges swept all sides of the volcano, killing nearly 3000 people. The eruption concluded with growth of a 560-m-high lava dome in the summit crater.